When I was a kid, boys played with toy guns, army men, played cops & robbers, King of the Hill, etc., and that seemed to be where they got their violent tendencies out.
Now guns are bad, the Army is evil, cops are demonized, etc., and there is no outlet for little boy behavior.
So, maybe video games are a way for boys to be boys?
I think so. We have three sons who are very active, play sports, are healthy and in good physical condition. But, they love to play videogames, too. We don't let them play the mature, violent, gory games, though. The article above goes on to say that the more mature games may lead to violent tendencies. Most of our kids' games involve auto racing, sports, etc. The only violence in their games involves boxing matches or shooting down planes.
For us, their parents, as long as the violence is not graphic and it involves a clearcut line between Good vs. Evil, and the player is on the side of Good, it's OK. For example, they would not be allowed to play a game like Grand Theft Auto or Doom.